1. Technical Field
The present disclosure relates to thermal field emission electron guns and methods for making and using same.
2. Description of the Background Art
A thermal field emission electron gun comprises an emitter tip that is heated by electric current and has applied electric field causing emission of electrons from the tip. Such an electron gun may be used in scanning electron microscopes and other similar instrumentation.
Cathode tip damage by arcing is the most frequent cause of electron gun failure. Arc events may occur during manufacture of the electron gun, during the first few weeks of field application of the electron gun, as well as during the rest of its operational lifetime. Most electron guns returned from the field failed due to arcing well before exhaustion of the potential lifetime of the gun. In practice, the useful lifetimes of such electron guns are typically limited by arcing from the emitter tip. This results in an undesirably frequent need for electron gun replacement.
Multiple previous improvements in materials and technology did not eliminate or sufficiently reduce the risk of arcing. It is desirable to improve the reliability and useful lifetimes of emitter tips in thermal field emission electron guns.